[ntp:questions] NTP 4.2.2p4 loopstats

TomD Thomas.Donovan at gmail.com
Mon Nov 13 20:51:33 UTC 2006


Dave,

re: "the clock discipline jitter has been separated from the selection
jitter"
& "loopstats have not changed in many years"
& "This is the same data reported over two decades"

No problem with separating the two jitters - but it was a surprise that
the loopstats jitter field  switched to reporting only the new
clock_jitter, rather than continuing to report sys_jitter starting with
NTP 4.2.2.

clock_jitter appears to be a 3rd derivative vs. sys_jitter which
appears to be a 2nd derivative of the clock offset.  Is that correct?

Graphing the jitter value from loopstats shows a much smaller value
starting with 4.2.2.  It doesn't correspond clearly to real-world
things like network load, as it did before the change. (although I
haven't collected enough of the new 'jitter' values to be sure of this)

-tom-

p.s. This topic seems to have gotten out of hand.  The original
question was "did jitter in loopstats change" and "what's a simple
definition of the new value".

Well, at least we've answered jg's first question:  'Yes, but the old
value is still available with a small code change.'

I'm a little taken aback by all the other things this topic has
meandered into: e.g. *what values ntpq displays, *what it calls them,
*the ntpq op command,  *the ntpq opeers value (bug 666), *ntpdc,
*ntp.isc->udel download links, *the other loopstats fields, *projects
to design new analysis mechanisms, etc. etc. etc.  Yikes!




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